spam.thruhere.netThis would help me very much.
Please note that you must not do this with a domain that you want to receive mail for. All mails sent to the host are rejected, so you probably will lose mail.
But you are safe to set the MX for old or abandoned domains. The more spam it received the better the domain is.
If you provide a very good domain (with uncountable spams) I'm willingly to buy that domain from you. To give you feedback on a domain you should write a mail telling me which domain you set to spam.thruhere.net and I will respond.